The following relates generally to wireless communication, and more specifically to cross-sub-band quasi co-location (QCL) signaling.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system, or a New Radio (NR) system). A wireless multiple-access communications system may include a number of base stations or access network nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
In some wireless multiple-access communications systems, devices may transmit and receive communications over multiple antennas. For example, a device may transmit parallel data streams over respective antennas in order to increase throughput (e.g., as opposed to transmitting the data streams sequentially over the same antenna). Additionally or alternatively, a device may transmit a given data stream over multiple antennas simultaneously (e.g., to increase the range of the transmissions). In some cases, the use of multiple antennas may be based on one or more antenna ports. An antenna port is a logical entity used to map data streams to antennas. A given antenna port may drive transmissions from one or more antennas (e.g., and resolve signal components received over one or more antennas).
Each antenna port may be associated with a reference signal (e.g., which may allow the receiver to distinguish data streams associated with the different antenna ports in a received transmission). Some antenna ports may be referred to as quasi co-located, meaning that the spatial parameters of the channel over which a symbol on one antenna port is conveyed can be inferred from the spatial parameters of the channel over which a symbol on another antenna port is conveyed. This implicit relationship between antenna ports may improve the reliability of successfully decoding a transmission. However, such an implicit relationship may not be discernible in all situations. For example, two devices may communicate over multiple sub-bands (or carriers) simultaneously. Because these sub-bands may or may not be associated with the same set of antennas at the transmitting device (e.g., a base station), a receiving device (e.g., a UE) may not be able to assume any implicit relationship between antenna ports of the different carriers (e.g., even if these antenna ports would be quasi co-located if they were transmitted over the same carrier).